Portable batch type dryer



1952 A. ANDERSEN, JR

PORTABLE BATCH TYPE DRYER 5 Sheets-Sheet 1 Filed July 10. 1957 55 .FarJfer a? Karrie?" Jzffarneys 1962 A. ANDERSEN, JR 3,056,214

PORTABLE BATCH TYPE DRYER Filed July 10. 1957 5 Sheets-Sheet 2 In 2/6/7107" flrlzzr jrzdensezgf."

63 far/fer Carzei" JZf/arze eg s Oct. 2, 1962 A. ANDERSEN, JR

PORTABLE BATCH TYPE DRYER 5 Sheets-Sheet 5 Filed July 10, 1957 Oct. 2, 1962 A. ANDERSEN, JR

PORTABLE BATCH TYPE DRYER 5 Sheets-Sheet 5 Filed July 10. 1957 Inventor Art/L 20' An dens'en, J1.

Parker 8:! C arier Attorney nit rates atent 3,656,214 PSRTABLE fiA'I Ci-i TYRE DRYER Arthur Andersen, In, Box ESQ, Republic, Mich. Filed .Iuiy 1d, 1957, Ser. No. 673,552 3 Claims. (63!. 34-45) My invention relates to improvements in dryers of the portable batch type for grain or other granular, lumpy or comminuted material, and has for one object to provide automatic control means whereby after the necessary adjustments have been made by the operator, batch after batch will be cycled automatically without further attention through the dryer.

Another object of my invention is to provide such controls and safety devices as will prevent start of operation and will stop operation when anything is wrong. Thus the material to be dried and the apparatus are both protected against damage in the event that no attendant is present to make corrections.

Other objects will appear from time to time in the specification and claims.

My invention is illustrated as applied to a type of grain dryer wherein two generally concentric horizontally disposed tubular foraminous walls define a generally annular bin, enclosing a plenum chamber, into which hot gas for drying, or cold air for cooling after drying, may be forced under pressure to pass radially out through the column of material held in the bin.

The operation will consist in a series of successive complete cycles. Each cycle includes filling, drying, refill after shrinkage, cooling and discharge and when the discharge stage is completed, a new filling stage will be inaugurated and the cycle will be repeated.

The operator is charged with the responsibility of making sure that an adequate supply of material to be dried is available and will set a control for the desired drying time. Having done this, he supplies by any suitable means, electric current to the apparatus. He pushes a button to automatically light the pilot light in the burner and when the pilot light is in operation, he then pushes the starter button to start operation. Thereafter cycling will continue, as long as there is grain available to be dried, fuel available to furnish the drying heat and temperature of the drying gas does not exceed a predetermined safe limit.

Assuming then that material, power and heat are all available because in the absence of any one of them the automatic cycling will not start, grain will be fed into the bin until it is full and the column of grain has reached its maximum height.

At that time feed will automatically stop, the pilot light will light the burner and the fan will force hot gas into the plenum chamber inside the bin and this hot gas as it passes out through the column of grain will dry it. As the grain dries, it shrinks, the grain column is reduced in height and additional Wet grain must be supplied to keep the column full. A switch, responding to the absence of grain, the column having shrunk, stops the fan and heat and starts the feed auger to bring in more grain and such stopping, and starting of the feed auger continues during the entire drying stage to maintain the column uniform in height.

When the timer indicates that a suiiicient drying time has elapsed, it automatically shuts off the burner while continuing power to the fan to force cold air instead of hot gas through the column of grain, thus cooling the grain down to the temperature, below the drying temperature, desired for storage.

When safe storage temperature has been reached, the fan will stop and the anger at the bottom of the bin will commence to discharge the dried, cooled grain, and discharge will continue until the bin is empty.

3&56214 When the bin has been entirely emptied, a sensing element or switch at the bottom of the bin, sensing the absence of grain will start the next cycle, the operation of which is the same as the first cycle, except that in the first instance the operator must throw the switch to start operaion. In all successive cycles, the sensing means in the bottom of the bin determines the absence of grain and starts the successive cycle.

While my invention is primarily adapted to the drying of grain, it could, of course, be used for drying of other granular material and while I have referred to grain for convenience, it is understood that my invention is not so limited and that grain is used as a generic term to describe any granular or nodular material, even coal, ore, sand or any other material needed to be dried which is sufificiently comminuted and where the particles are of such size that they will flow under gravity or under the impulse of the feed auger.

My invention is illustrated more or less diagrammatically in the accompanying drawing, wherein- FIGURE 1 is a perspective View of the grain dryer;

FIGURE 2 is a transverse vertical cross section through the dryer;

FIGURE 3 is a longitudinal vertical cross section through the dryer taken along the line 3-3 of FIG- URE 2;

FIGURE 4 is a diagramamtic representation of the operating and safety control system;

FIGURE 5 is a perspective view of the outside front end of the dryer;

FIGURE 6 is a section on an enlarged scale along the line 6--6 of FIGURE 5.

Like parts are indicated by like characters throughout the specification and drawings.

Inner and outer forarninous bin walls 1 and 2 are joined by vertical front and back walls 3 and 4 to define a generally annular, horizontally disposed drying bin encircling a hot gas plenum chamber 5 into which may be discharged hot products of combustion from the burner housing 6. The details of the burner including the pilot light and fuel supply are not further illustrated. A fan 7 driven by motor 8 supplies air for combustion and forces the hot gas into the plenum chamber 5 whence it passes out through the grain column in the annular bin to dry the grain. After the gas has passed through the grain, it escapes to the atmosphere through the outer foraminous wall 2.

The filling hopper 9 discharges through duct 10 in back wall 4 to the top of the bin. A feeder auger 11 driven by motor 12 extends from the bottom of the hopper 9 through duct 10 to the front wall 3. The feed auger thus extends clear across the upper boundary of the drying column contained in the drying bin. A discharge auger 13 driven by motor 14 extends clear across the drying bin from the front wall 3, at the bottom of the column for discharge through the duct 15 in the back wall 4. A control cabinet 16 on the front Wall 3 con tains control and safety elements as will later be described.

In the control cabinet 16 are a time clock 21 which may be set to any desired drying time. Cabinet 16 also contains on and off control push button switch 22 by which the operator may start or stopthe operation. In the filling hopper 9 or at any other suitable point in the wet grain supply system, exposed to the pressure of the grain is a wet grain supply pressure sensitive control switch 23 which senses the presence or absence of grain and prevents operation of the dryer when wet grain is not present and available. On the front wall 3 at the top of the column and adjacent to the discharge end of the feed screw 11 is a full load control pressure sensitive switch 24, which, when the bin is full and the column is at maximum height, responds to grain pressure built up by the screw and gravity to shut off power to the motor 12, but which, as the grain shrinks in drying, senses the reduction in pressure resulting from the shortening of the column and calls for operation of the feed screw 11 to provide make up wet grain to bring the column back to full height.

When the pre-set drying time has elapsed, the time clock 21 shuts off the burner but the fan 7 continues to force ambient air for cooling into the plenum chamber 5. This continues until the grain has reached the desired temperature for storing. At this point the cooling temperature control switch 28 responsive to the temperature of the grain in the bin will shut off the fan 7, the discharge motor 14 will be started and will unload the bin.

When the bin is empty pressure sensitive empty switch 26 will supply momentary contact to start the timer 21 on the heat and load cycle when the entire operation will be automatically repeated. The position of the plenum chamber is such that the grain column between the walls 1 and 2 is thinner at the top than at the bottom and sides. Resistance to flow of hot gas through the make up grain in this area of relative column thinness is enough less than resistance elsewhere that more hot gas will pass through the make up grain. The make up grain being thus exposed to more gas for a shorter length of time will also be adequately dried.

Since my dryer while portable is to be used where grain is in storage on farms and the like and since such farms habitually have electric current available, the power to operated and control my dryer is preferably though not necessarily electric. The fan and augers might be driven by internal combustion engines and the controls might be pneumatic or hydraulic. The fuel for the burner is preferably bottled or natural gas, but oil or any other fuel may be used and any standard burner with conven tional self-ignition may be used.

In the modified form shown in FIGURES and 6, pressure sensitive switch 24 takes the form of a hopper 4% communicating with the interior of the bin bounded on its lower side by a flexible diaphragm 4M upwardly and outwardly inclined. 492 is the switch member actuated by the diaphragm. The diaphragm will yield to actuate the switch both in response to the pressure generated by the auger 11 and in response to the weight of the grain resting on its as an inclined floor.

The use and operation of my inveniton are as follows:

The operator connects current to the machine. He sets the time clock 21 for the time necessary to adequately dry the material. He sets the operating temperature control switch 27 for the temperature of the hot gas necessary to dry the grain. He sets the cooling temperature control switch 28 for the temperature desired for storage. He makes certain that there is a supply of material to be dried, sufiicient in quantity for automatic operation. At least ten percent or more than the individual batch should be present before work starts.

He then pushes switch button 29 to light the pilot light in the pilot circuit, thus by-passing the pilot control relay 34 and opening the pilot solenoid valve 30 closing a circuit through ignition transformer 31 so that the pilot will have gas supply and ignition. When the pilot has been lighted and sufiicient heat has been developed to energize the thermocouple lead through pilot control relay 34, he can take his finger oil the push button 29 because the control relay will hold the circuit closed.

Should the pilot fail, the circuit will be opened by the pilot control relay 34 and gas supply will be shut oil by pilot gas supply solenoid operated valve 30. A pressure drop will then occur when the demand for heat opens temperature controlled solenoid valve 32., causing a drop in pressure between solenoid control valves 30 and 32. At this point low pressure shut off switch 33 as a result of drop in pressure will open, causing magnetic 4 circuit switch 340 to open and the entire system beyond the pilot circuit will be shut off.

If the circuit remains operative and if the supply of grain is present as sensed by pressure sensitive switch 23 and if the temperature is within the safe limits as sensed by the high temperature limit switch 35 and if adequate gas pressure is available as sensed by low pressure shut off switch 33 and if the overload heat circuit is closed by the overload heater coil 36, then when operator closes on and ofi switch 22 or when the machine is recycling, the momentary contact switch 26 sensing that the bin is empty makes contact, the machine will start operation and loading will commence.

The loading motor 12 will load the bin and current will be supplied through the loading motor outlet box 37 if necessary to operate a separate loading motor not illustrated to feed grain to the hopper 9. When the drying column is filled, pressure sensitive full load switch 24 will open, causing relay 43 to open the circuit to loading motor 12, causing the loading motor to stop the feed. At the same time, the fan control relay 39 will close the circuit to the magnetic contactor 40 causing the fan motor 8 to start. 38 is a full load control manually operable switch. At the same time the heat circuit control switch 34-1 will close the heat circuit, starting the fire which will continue to raise the temperature of the drying gas until operating temperature control 27 opens when preset temperature has been reached. Thus during the initial loading and during reloading to compensate for shrinkage, the fan and heat circuits are open so that the power demand on the farmers electric system is either the loading load or the drying load but never both at once.

Under these circumstances the burner will cycle on and off to maintain the preset temperature. One line obtains current from one side of the loading circuit, the other volts is obtained from one side of the fan motor circuit at the junction point 42 so that if the fan is not receiving current through the magnetic fan contactor as, the heat circuit will not operate. This is a safety feature to insure that there is air to support combustion.

The loading motor continues to operate until a full load has been supplied to the bin at which time full load pressure sensitive switch 24 senses the drying chamber is fully loaded and stops the feed. When shrinkage of the mass occurs due to removal of moisture, the column shrinks in height, the pressure drops off and switch 24 senses the shrinkage and closes the loading motor circuit until the bin is again full. This happens periodically as drying and shrinkage continue.

When the time for which the clock 21 has been set has elapsed, it opens the load and heat circuits by the double pole, double throw switch 43 and the cooling and unloading circuit will be closed. However, the fan will continue to operate to cool the material until the cooling temperature control 28 reaches the preset cooling temperature. At this point, the circuit is closed through the unloading motor 14 and if desired, means to convey material away from the machine may also receive current through the unloading auger outlet box. The fan control relay 39 opens the fan holding circuit at 41 stopping the fan. Unloading will continue until the drying bin is emptied at which time momentary control switch 26 repeats the process.

If at any time, wet grain supply is exhausted, wet supply switch 23 sensing the absence of grain will open, shutting ofi the entire system.

The length of time necessary to dry the grain and the temperature at which the grain can safely be stored depend upon its character, and moisture content and may be determined in advance. Usually the grain will be stored at a temperature less than the temperature at which it is dried. The operator having made such determination, sets the timer and the cooling temperature controls accordingly. He then closes the master switch to cause the dryer to operate. If fuel, power and grain to be dried are available, closing the switch will start operatiOn but if any one is lacking, the dryer will not operate.

The dryer will operate in a series of successive cycles and each cycle includes the following steps: Grain is fed into the bin gradually filling it until the column of grain reaches the top of the bin, and the grain exerts a pressure on the pressure sensitive switch to stop the feed. The burner lights and the fan begins to force hot products of combustion into the plenum chamber so that they may pass out through the column to dry the grain. The grain shrinks as it dries and the height of the column decreases. Thus relieving the pressure of the grain at the top of the column and allowing the feed to be resumed until the column is again filled. This stopping and starting of the feed continues during the entire drying stage so that the column is always full to the top. Thus continuing periodic supply of make up grain is fed to the top of the column and such make up grain being located in a thinner portion of the column receives more heat for more rapid drying to compensate for the shorter time it is exposed.

At the time set, the timer turns oi the fuel and no more heat is supplied but the fan continues to force cool air into the plenum chamber which air as it passes out through the column cools the grain down toward the desired storage temperature. When such temperature is reached, the switch to supply current to the unloading motor is closed, the fan stopping operation immediately when the unloading motor starts to work and the unloading screw discharges the dried and cooled grain from the bin. Grain continues to be discharged until the bin is empty. When the bin is empty, the pressure sensitive switch at the bottom of the bin adjacent the point of discharge senses absence of grain, momentarily closes a circuit to start the reloading for the next cycle and the cycle is repeated as above.

If the operator has made a mistake and set the timer for too short a drying period, he can easily advance the timer without any other elfect except to delay the time when the timer shuts oi the fire to inaugurate the other sequence.

I claim:

1. In a grain drier comprising:

(a) a bin having inner and outer perforated side walls defining a drying column,

(b) a heater and means for circulating air through said heater and column,

(c) means for feeding grain to the top of said column,

(d) means for discharging grain from the bottom of said column,

(e) control means for said feeding means,

(1) a first pressure sensitive means adapted to contact the grain at the top of the column and connected to said control means to stop the operation of the feed means when the column is full,

(g) means actuated by said first sensitive means when the column is full to energize said heater and said air circulating means,

(h) said control means including a timer adapted to deenergize said heater when a predetermined drying time has elapsed,

(i) a thermostat adapted to sense the temperature of the grain in the column,

(j) means responsive to said thermostat to de-energize said air circulating means when the temperature of the grain has been lowered to a desired minimum and for simultaneously actuating said discharge means,

(It) second pressure sensitive means adapted to contact the grain at the bottom of the bin,

(1) and means actuated by said second sensitive means to de-energize said discharge means and reset said timer for another cycle.

2. In a grain drier comprising:

(a) a bin having inner and outer perforated side walls defining a drying column,

(b) a heater and means for circulating air through said heater and column,

(c) means for feeding grain to the top of said column,

(d) means for discharging grain from the bottom of said column,

(e) control means for said feeding means,

(1) a first pressure sensitive means adapted to contact the grain at the top of the column and connected to said control means to stop the operation of the feed means when the column is full,

(g) means actuated by said first sensitive means when the column is full to energize said heater and said air circulating means, said first pressure means sensing shrinkage of the grain after a period of time and thereafter operating to de-energize said heater and air circulating means and to re-energize said feeding means, the cycle of operation of the sensing means being repeated until the column becomes stabilized,

(h) and said control means including a timer adapted to thereafter de-energize said heater when a predetermined drying time has elapsed.

3. The apparatus of claim 2 and also including:

(i) a thermostat adapted to sense the temperature of the grain in the column,

(j) means responsive to said thermostat to de-energize said air circulating means when the temperature of the grain has been lowered to a desired minimum and for simultaneously actuating said discharge means,

(k) second pressure sensitive means adapted to contact the grain at the bottom of the bin,

(l) and means actuated by said second sensitive means to de-energize said discharge means and reset said timer for another cycle.

References Cited in the file of this patent UNITED STATES PATENTS 2,069,193 Behr et a1. Ian. 26, 1937 2,307,294 Persons Jan. 5, 1943 2,373,339 Roberts Apr. 10, 1945 2,654,961 Manecke Oct. 13, 1953 2,740,204 Seltzer et a1. Apr. 3, 1956 2,772,487 Arndt Dec. 4, 1956 

